1. Field of the Invention
The present invention is related to manually lever-shifted mechanical transmission systems having automated assist features including at least engine automation to achieve a substantially zero torque condition for shifting into neutral.
In particular, in a preferred embodiment, the present invention relates to a manually lever-shifted splitter-type compound mechanical transmission system including means to sense an operator intent to shift, an electronic control unit, an electronically controlled engine, and a three-position splitter actuator responsive to command output signals from the control unit. In the preferred embodiment, upon sensing an intent to shift, the electronic control unit is effective to cause automatic engine fueling to cause a substantially zero driveline torque, while urging the splitter actuator to splitter-neutral. Upon sensing a splitter-neutral condition, the automatic engine fueling to cause a substantially zero torque condition (preferably dithering intentially to cause a drive torque and then a coast torque condition, as described in U.S. Pat. No. 4,850,236) is ceased and the splitter retained in the splitter-neutral condition until a lever shift into main-section-neutral is sensed.
2. Description of the Prior Art
Fully automatic and semi-automatic vehicular mechanical transmission systems and fully or partially automated shift implementation systems utilizing electronic control units, usually microprocessor-based controllers, are known in the prior art. Examples of such automated mechanical transmission systems may be seen by reference to U.S. Pat. Nos. 3,961,546; 4,361,060; 4,425,620; 4,595,986; 4,631,679; 4,648,290; 4,722,248; 4,850,236; 5,038,627; 5,050,079; 5,053,959; 5,053,961; 5,053,962; 5,063,511; 5,081,588; 5,089,962; 5,089,965; 5,133,229; 5,172,609; 5,231,582; 5,272,939; 5,335,566; 5,435,212; 5,508,916 and 5,509,867, the disclosures of which are incorporated herein by reference.
Partially automated mechanical transmission systems having automatic splitter shifting and/or automatic shifting between the highest sequentially related group of ratios, and requiring manual shifting in the lower ratios, are known in the prior art, as may be seen by reference to aforementioned U.S. Pat. Nos. 4,722,248 and 4,850,236, and to U.S. Pat. Nos. 5,038,627; 5,393,277; 5,435,212 and 5,498,195, the disclosures of which are incorporated herein by reference.
Compound mechanical transmissions of the range, splitter or combined range-and-splitter type are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 3,799,002; 4,754,665; 4,920,815; 4,974,468; 5,000,060; 5,370,013 and 5,390,561, the disclosures of which are incorporated herein by reference.
Partially automated mechanical transmission systems providing automatic assistance, such as automatic engine fuel control, for manual lever-shifted transmissions are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,682,790; 5,755,639; 5,735,791; 5,743,143; 5,569,115; 5,571,059; 5,573,477 and 5,582,558, the disclosures of which are incorporated herein by reference. These systems utilize automatic engine fueling controls and/or range and/or splitter shift actuators, actuated by a driver indication of an intent to shift, allowing an old gear to be disengaged and a new or target gear to be engaged without requiring the driver to manipulate the clutch pedal (required only for vehicle launch and stop) or the throttle pedal.